The present invention relates to a flexible and easy-to-stretch hose that is crush resistant and well suited to provide a constant supply of air, anesthesia gas or gas-carried medication to a patient's face mask, nasal mask or tracheotomy tube for a variety of purposes such as anesthesia, life support or medication delivery, or to help prevent sleep apnea. Flexible, stretchable, crush resistant hoses embodying features of the invention are also well suited to evacuate gaseous pollutants from surgical areas, such as the removal of smoke during laser surgery.
Some prior crush resistant plastic hose proposals call for the use of solvents or glues to bond a web of thin material to coils of a helix that cooperate with the web to give the resulting hose its crush resistance. However, the use of solvents in the manufacture of crush resistant hoses is undesirable in medical applications because the resulting hoses may bring the patient into contact with trace amounts of the manufacturing solvent or glue, or the solvent or glue may react undesirably with medication being administered through the hose to a patient.
Some prior crush resistant plastic hose proposals intended for medical use are produced by extruding a thin web of plastic material to provide a connecting wall extending between adjacent coils of helix of plastic. This connecting web may take a wavey form or may incorporate accordion-like folds that enable the hose to extend and contract in an accordion-like manner to give the resulting hose a measure of flexibility.
Although the hoses that result from the process just described may be effective in delivering air or gas-borne substances to the patient, the nature of the extrusion process used to produce these hose products typically causes the resulting hoses to exhibit a high degree of torsional stiffness and a diminished degree of flexibility due to the orientation of the molecules that form not only the thin wavy wall but also the helix that enhances the crush resistance of the hose. The torsional stiffness can cause a patient's face mask or nasal mask to lift off the face during movements of the patient's head, thereby allowing unwanted ambient air to enter the breathing circuit during therapy. The stiff nature of existing products also may cause undesirable stress on a tracheotomy tube during patient movement, and can render difficult head movements of a patient.